Data storage systems are often used to store large quantities of data with fast access times. Redundant Array of Independent Disk (RAID) technology is often used to provide increased data availability and reliability by storing redundant information (e.g., parity) across a set of disks within a RAID group.
In some architectures, declustered RAID is used to reduce the rebuild time in case of a failure. In such systems, a cluster of disks can store several RAID groups dispersed across the cluster. This approach provides speed and flexibility in the event of a disk failure, especially when a level of RAID involving parity (for example, RAID 5 with one parity member or RAID 6 with two parity members) is used, since reconstruction of the data from the different RAID groups stored on the failed disk typically involves reading from a diverse set of disks associated with each RAID group. There is also flexibility because entire spare drives need not be kept, but rather only spare sections of disks, and the data from the different RAID groups stored on the failed disk may be reconstructed onto several different spare areas.